Sensory aid for the blind



y 7, 1957 J. E. BERRY 2,791,762

SENSORY AID FOR THE BLIND Filed April 14, 1955 INVENTOR (2222 EBerr yATTORNEYS SENSORY AID FOR TEE BLIND John Ervin Berry, Van Nuys, Califi,assignor to General Networks, North Hollywood, Calif., a corporation ofCalifornia Application April 14, 1955, Serial No. 501,279

6 Claims. (Cl. 340-258) The primary object of this invention is toprovide a sensory aid for blind persons, and more particularly, theprovision of an electrically equipped cane or the like which senses andindicates the nature of the area surrounding the cane.

The invention embodies an oscillation system which is made to produce anaudible tone upon the change of capacitance reflected into a circuit bymeans of a probing antenna. In other words, movement of an object orother variable factor in predeterminable relation to an apparatusembodying the invention, or movement of the apparatus relative to anobject, causes variations in the capacity of the oscillating system,which in turn brings about variations in the frequency of oscillation ofthe system and such frequency variations provide audible tones.

With the use of a cane equipped with electrical apparatus according tothis invention, a blind person may have better contact with hisenvironment. As he moves through a room, along the sidewalk, across thestreet, etc., the omnipresent electrostatic fields of his immediatesurroundings combine to have a definite, capacitive effect upon theprobing antenna. Different surroundings will produce difierentcapacitive effects, and therefore, a variety of audio tones areavailable.

These different tones soon become distinctive to a blind person, andeach will apprise him of a particular condition in his surroundings. Forexample, they will inform him of the presence or approach of objects inhis pathway and give him the relative distance to such objects. Theywill give him warning when he is ap proaching a sudden change of contourin his path or his surroundings and will provide a constant signal whenhe is walking along a sidewalk, for example, or beside a building. Thus,with this invention a blind person no longer needs to feel his way alongwith an ordinary cane in the conventional tapping manner.

Therefore, another object of this invention is to provide electricalapparatus for a blind person, so that he may easily be apprised of thecondition of his surroundmgs.

More specifically, an object of the invention is to cause saidelectrical apparatus to produce an audible tone, the frequency of whichis relative mainly to the non-atmospheric environment.

It is another object of this invention to produce said audible tone forthe stated purposes by the principle of heterodyning.

Other objects of the invention and the full scope thereof will beapparent from the following specification and appended claims incombination with the appurtenant drawings in which:

Figure 1 illustrates exemplary apparatus embodying the invention; and

Figure 2 is a schematic drawing of an exemplary oscillation systemsuitable for practicing the invention.

In reference to Figure 1, there is shown an exemplary sensory aid inaccordance with this invention comprising a cane 16 having a handle 12and a leg portion 14. Affixed to the upper part of the leg 14 by clamps16 2,791,762 Patented May 7, 1957 and 18 is an oscillation system in aunit 20. The antenna comprises a wire or flexible lead 22 which ismounted by antenna clips 24 to the leg 14 at intervals during itsextension therealong from the oscillation unit 20 to the tip 26. Antenna22-has a definite normal capacity, and this capacity is aifected bysurrounding objects, the result of which is to change the frequency ofthe oscillation system in unit 20. Connected to unit 20 by connector 28and leads 30 is a hearing aid type earphone 32 which reproduces audiblythe result of frequency changes in the oscillation system. The audiofrequency may be adjusted by tuning knob 34 (to be explained more fullyhereinafter), and switch 36 turns the electrical unit 20 01f or on.

It will be appreciated that many varieties of oscillators may beutilized within the unit 20 to produce an audio tone, the only criterionbeing that the circuit be capable of responding suitably to changesreflected thereto by the antenna. Therefore, not only a regular audiooscillator but beat-frequency or heterodyne oscillators may be used.Figure 2 illustrates the use of heterodyning oscillators, this being thepreferable method of obtaining the audio tones. The two oscillatorcircuits 4t) and 42 contained within dash lines 40 and 42",respectively, are each illustrated as a species of the well knownHartley oscillator. Again this is merely an exemplary showing, theshunt-feed Hartley, Colpitts, Meissner, tickler feedback, reversefeedback, tuned-plate, tuned-grid, crystal, magnetostriction,negative-resistance, relaxation, transistor, or saturable reactoroscillators, to name but a few, being just as suitable. lator circuits4t and 42 are illustrated as being of the same type, no limitationthereto is intended since, for example, oscillator 40 could be a crystalcontrolled circuit while oscillator 42 could be any of the other typeoscillators.

With reference now to Figure 2 in detail, .it will be noted that eachexemplary oscillator circuit 40, 42 contains a pentode tube 44 whosescreen grid is connected by a line 46 to its plate electrode 48 andwhose suppressor grid is tied to its cathode 50. The filament 52 foreach pentode 44 is supplied with heating power by batteries 54,respectively, and a double pole single throw switch 36 having a pole 56in each filament-battery circuit.

Producing the oscillations in conjunction with each tube 44 is a tankcircuit 58 for oscillation circuit 40 and a similar tank circuit 60 foroscillation circuit 42. Each tank circuit 58, 60 has an oscillator coil62 which is tapped at points 64 and 66, the former tap being coupled bygrid-leak condenser 68 to the control grid 70 and the latter viaresistor 72 to cathode 50. Across the whole of coil 62 is connected acondenser to complete each tank circuit 58, 60. The condenser 74 inparallel with coil 62 in tank circuit 58 is preferably (but need not be)a variable condenser, as indicated by the arrow 76, and may be varied bythe tuning knob 34 shown in Figure 1. However, the condenser 78,paralleling coil 62 in tank circuit 60, is preferably (but need not be)a fixed condenser, but attached to the tank circuit 60 at junction 61 isantenna 22 whose capacitance is effectively varied according to itssurroundings, as previously explained. The effective capacity of antenna22 may be considered to be in parallel with condenser '78 at all timesand therefore effects the impedance of tank circuit 60 to vary thefrequency thereof. Each tube 44 obtains its control grid 70 operatingbias through resistor which is connected thereto and to the bottom ofeach coil 62.

The oscillations circuits 40 and 42 are connected in parallel with eachother by interconnecting the tank circuits with a line 82 and the plateelectrodes 48 with a line 84. Between lines 82 and 84 is connected theoscil- Also, even though the two oscillationsustaining battery86-and"earphone-32,' each of which is paralleled by an R.-F. bypasscondenser 88 and 90, respectively. Since the two oscillation circuitsare in parallel, their frequencies of oscillation beat together and bywell known heterodyne principles form a difference frequency when theirfrequencies'of oscillation differ in the least. The difference frequencyis utilized directly, in this example, as the audio tone in'the earphone32;

The operation of the sensory aid is as follows: The blind .personfirstturns on switch 36'WhlCl1 immediately allows each self-excitedoscillation circuit 40, 42 to begin generating oscillations to produceanaudio tone in earphone 32 if the oscillations .in 'the'two circuitsdiffer in frequency. The operator may then adjust reference oscillator40 with tuning knob 34- to cause a definite and familiarly pitched audiotone (or, alternatively, a zero beat-no audio tone) to appear inearphone 32 while he has the cane leg 14, and consequently the antenna22, related in a predetermined position to a predetermined object or thelike. Upon moving the cane 'leg 14, the operator will hear a new audiotone if the surrounding objects, terrain, and/ or contours becomedifferent, since the effective antenna capacitance varies with thesurroundings. In a short time, a blind person with his acute senses willbe able to distinguish'a multitude of tones and relate each toparticular surroundings.

The cane can, of course, be utilized in the conventional manner at thesame time as it is being used in accordance with this invention.However, it is not necessary at all that a cane per se be used in thepractice of this invention as long as the oscillation system has somesort of holder for the operator to handle and a movable antenna.-

higher the operating frequency of oscillation circuits 40" and 42, theless percentage change is necessary in the frequency of circuit 42, andconsequently, in the antenna capacity, to produce the sameaudio-difference frequency.

Therefore, the system can be made to respond to changes insurroundings.when said changes are within predetermined large or small distancelimits according to the operating frequency of thesystem. Satisfactorysensitivity has been found. .to' exist with apparatus of thetype-illustrated when the operating frequency thereof was in the 75 kc.band. Values of circuit elements for operation at that frequency are asfollows, although; it will be understood that'the invention is notlimited. to the frequency noted or the values listed:

Tubes 44 CK-542 pentode Condensers 68." 150 mmf. Condenser 74 ()45 mmf.Condensers 78 Smmf.

Condenser 88, 1 mt.

Condenser 99 1 .002 mf.

Resistors 72 1200 ohms, /3 watt. Resistors 80 lmegohm, /3 Watt.Batteries 54 l /z volts.

Battery. 86 22 /2'volts.

Modifications of this invention not'described herein will becomeapparentto'those skilled in'the art." There fore, it isintended-thatthe'matter containedintheforegoing description beinterpreted-its-illustrative and not tion systcnrforproducingfrequencies in the audio range,-

said system having a tank circuit of variable impedance, and saidfrequencies in the audio range corresponding respectively to thevariations of said tank circuit impedance, an antenna coupled to saidtank circuit for varying the impedance thereof in accordance with thesurroundings of said antenna, and means for holding said oscillationsystem and said antenna, said holding means comprising a cane-likestructure.

2. A sensory aid for the blind comprising an oscillation system forproducing frequencies in the audio range, an antenna coupled totheoscillation system, said antenna having a variable effective capacitanceand said frequencies in the audio range corresponding respectively tothe variations of said effective capacitance, and means comprising acane-like structure for holding said oscillation system and antenna, thearrangement being such that the effective capacitance of the antennavaries in accordance with its surroundings.

3. A sensory aid for the blind comprising an oscillatiQn"-system forproducing difference frequencies in the audio range, an antennaconnected to the oscillation systern, said antenna having a variableeffective capacitance and'said difierence frequencies correspondingrespectively to the variations of said effective capacitance, and'meanscomprising a cane-like structure for holding said oscillation system'andantenna, the arrangement being such'that the effective capacitance ofthe antenna varies in accordance with its surroundings.

lfA sensory'aid for the blind comprising a cane-like structure forholding a unit including a reference frequency oscillatorand' a variablefrequency oscillator interconnected in parallel to produce differencefrequencies in the audio rangefan'd an antenna connected to the variable 'frequenc'y oscillator, said antenna having a variable effectivecapacitance and said difference frequencies corresponding respectivelyto the operating frequencies of said variable frequency oscillator andthereby to the variations of said effective capacitance, the arrangementbeing such that the effective capacitance of the antenna varie'sinaccordance with its surroundings.

5. Ascnso'ry aid for the blind comprising a cane-like structure forholding a unit including an adjustable reference frequency oscillatorand'a variable frequency oscillater'interoonnected in parallel toproduce difference frequencie's in the audio range, and an antennahaving a variable effective capacitance and said difference frequenciescorresponding respectively to. the operating frequencies of saidvariablefrequency oscillator and thereby to the variations of said effectivecapacitance, the arrangement being such that the effective capacitanceof the antenna varies in accordance with its surroundings.

6. A sensory aid for the blind comprising a cane-like structure forholding a unit including a Hartley type reference frequency oscillatorand a Hartley type variable frequency oscillator interconnected inparallel to produce difference frequencies in the audio range, means'todetect said'difference frequencies and an antenna having a variableeffective capacitance and said difference frequencies correspondingrespectively to the operating frequency of said variable frequencyoscillator and thereby to the variations of saideifective capacitance,the arrangement being such that the effective capacitance of the antennavaries in accordance with its surroundings.

References Cited in the file of this patent UNITED STATES PATENTS1,820,357 Lindstrom et a1. Aug-25,1931 2,112,826- Cook Apr. 5, 19382,238,041 Dickens Apr. 15, 1941 OTHER REFERENCES Article on pages 186and 188 of the November 1954 issue of Electronics, titled, Cane GuidesSightless.

